There's obviously no legal recourse to someone reading from our wiki and passing it off as their own work. It's all public domain.
But pilfering our work like that is a dickish move, plain and simple.
We (or I, at least) always cite an original source when we use one, because that's just fair and correct. Christ, I've lifted more from the Weyland-Yutani Archives, Strange Shapes, Monster Legacy and this very site than I can think of, but they always get a citation when I do. Because guess what? The hard work was theirs.